I've got several sets of powerbites with different pedal bosses. I have had this problem aswell even on my newer hollowbites. If it is the sort with the lock ring on the back, I took the pedal all the way out with the insert. Carefully clamped it in a vise at work sprayed with WD40 and left for awhile. Then undid the pedal. Cleaned everything throughly, Getting all the old lock-tite off. Then re-applied lock-tite and put it back together. I now put grease on my pedal threads and just nip them up.